Pollution prevention and/or control is of great importance to both public health and safety as well as the preservation and protection of the environment. Pollution control and especially the control of toxic substances is a growing concern worldwide and has become extremely important to protect the environment from contamination and/or destruction.
Systems conveying fluids such as water which is otherwise substantially contamination-free normally direct said fluid flow to an intermediate or final destination such that fluid flow is normally unrestrained, i.e. is neither diverted, normally diverted nor regulated nor blocked during normal conditions. However, in situations where toxic materials or the like may be introduced into a fluid flow due to an accident or man-made or natural catastrophe, it is desirous to block fluid flow at one or more locations along a conveying network in order to prevent the toxic materials from reaching certain destinations which would either cause severe harm to the environment or other significant problems such as the necessity for performing expensive cleanup operations.
It is therefore important to be able to provide apparatus capable of rapidly and reliably blocking fluid flow within a conveying conduit in a rapid and reliable manner substantially immediately upon an indication that a contaminating condition is present or may develop. It is also important to be able to promptly react to such conditions detected by sensor means located at a remote upstream location from the place at which flow blockage is to occur. It is further important to provide a system which provides either no or substantially no blockage to fluid flow during normal flow conditions and which operates automatically and without the need for human intervention.